Ammonium nitrate-chromate salt explosive compositions



v plosives.

United States Patent O Y 3,166,450 AMMQNIUM NITRATE-CHRQMATE SALT EXPLUSEVE COMIDSITIGNS 1 CharlesW. Kaurmm, New Haven, Comm, assignor, by

mesne assignments, to Commercial Solvents Corporation, a corporation of Maryiand V r No Drawing. Filed May 1, 1961, Ser. No. 196,455 11 Dianna. (Cl. 1d946) invention is to provide ammonium nitrate'explosive com.-

positionswhich produces a detonation of useful magnitude and force upon proper initiation. Another objectof this invention is to provide ammonium nitrate explosive compositions of greatly increasedpower. Another object of this invention is to provide ammonium nitrate explosive compositions containing a chromate salt;

Another object of this invention is to provide an improved ammonium nitrate composition suitable for use in explosives.

Iii-the first step of preparing the novel explosive cornpositions of this invention a chromate salt is admixed with molten ammonium nitrate at a temperature from about 170 C. to about 209 C. to form a melt containing from about 0.5 to about percent of the chromate-salt based on the-weight of the ammonium nitrate. In-the second step the novel ammonium nitrate composition of this invention is formed by converting the ammonium nitrate-chromate saltmelt into a solid particulate material. This can be accomplished by allowing'the melt to solidify and subjecting the solid material so produced to a'size reduction process thus forming a granular product or the melt can be sprayed in small droplets in a tower high enough to allow solidification of the droplets during free fall thus forming prills or granules. In the case of the prilled product a coating of clay, diatomaceous earth, chalk, etc. can be applied to reduce caking. In the third and final step, a hydrocarbon oil is admixed with the ammonium nitrate composition in particulate form in an amount such that the resulting explosive composition contains from about 3 to about 8 percent of oil based on the weight of the particulate material.

In making explosive compositions containing the novel ammonium nitrate composition, prepared as described herein, a particle size range of from about 3 to aboutlOO meshcan be utilized. The use of the ammonium nitrate composition of this invention is not limited to the novel 1 rotary crusher.

I fractions and mixtures thereof, kerosene, etc.

the art, for example, by means of a hammer mill or a In addition, prills or granules can be prepared from the ammonium nitrate-chromate salt melt in conventional prilling equipment.

Suitable hydrocarbon oils are those which are liquid at room temperature and pressure. Such liquids have little or no solvent action on ammonium nitrate. Useful hydrocarbon oils include crude oil, fuel oil, lubricating oil Hydrocarbon oil can be admixed with the ammonium nitratechromate'salt materialin a wide variety of equipment such as in a ribbon mixer, a tumbling barrel or 'in a double cone mixer. i l v In' general, ammonium nitrate ofany desired particle size which can be charged conveniently to'the melting v apparatus can be used with equalease to prepare the novel ing diameter of about 2.5 inches. charge was placed in a suitable hole in such a manner t that in each instance the top of'the charge inthe container was flush with the ground. A blasting cap,'which in g each test was an Engineer Special Blasting Cap or equiva- Y ammonium nitrate con positi'ons of this invention..

To'demonstrate the properties of the novel explosive .i Ompositions of this invention a variety of compositions were prepared and detonated in the field. Detonation was achieved by means of an electric blasting cap, such as an Engineer Special Blasting Cap. The charges as tested were packaged in" cylindrical paper containers hav- The container with the lent, was placed in the explosive charge through the open top of the container and the composition detonated by closing the firing switch. The magnitude of the detonation obtained in each test was determined by measuring'the size of the crater produced. Although it is true that the veniently added to the molten ammonium nitrate in the form of the granular material having a mesh size of fromg about 4 to about 200.

The solid product formed on solidification of the am- [3 monium nitrate-chromate salt meltcan be reduced to a i granular material by any of the methods well known top 1 crater size alone is not indicative of the amount ofearth formation that is broken up, it does give an indication of the workpotential of the mixture detonated. In a like manner'ammoniumnitrate-oil explosive compositions containing 5.0 percent No. 2 Dieseloil based on the weight of the ammonium nitrate but without a chromate salt were prepared from fused ammonium nitrate and detonated Results of under the same conditions for comparison. these tests showed that the novel compositions'of this invention exhibit substantially greater work potential than those compositions not containing a chromate material. For example, on detonation of a composition containing ammonium nitrate containing 3 percent potassium dichromate based on the weight of the ammonium nitrate and having 5 percent No. 2 Diesel "oil based on the combined weight of the ammonium nitrate and potassium dichromate a crater having a volume of 3270 cubic inches was formed as compared to a crater volume of 1390 cubic inches when an ammonium nitrate explosive composition containing 5 percent of No. 2 Diesel oil based on the weight of'the ammonium nitrate was'detonated under the same conditions.

The novel explosive compositions of this invention can be charged directly into aborehole and detonated by means EXAMPLE I Granular ammonium nitrate in the amount of 300- grarns (particle size, percent through 40 mesh) was added to acasserole and then heated-on an electric heater until molten. As soon as the ammonium nitratehad all melted, the temperature was raised to. C. In the" Patentedv Jan. 19, 1965 of the ammonium nitrate.

to the molten ammonium nitrate with stirring. During the addition of the potassium dichromatethe melt turned brown and there was some evolution of gas. As soon as a homogeneous melt system had been achieved, the melt was poured into a casserole and allowed to cool. The solid ammonium nitrate containing potassium dichromate was ground in a mortar, passed throughaseries of standard screens to determine the size distribution of the particles and then the sieved fractions were mixed withthose from two other batches prepared in the same manner; For the combined batches the particle size distribution was as follows.

Mesh size: Percent 3-14 .59 l4-24 Fines V V o EXAMPLES II. and III 7 T wo explosive compositions containing ammonium nitrate, sodium dichromate and N0. 2 Diesel oil (see Ex- 7 amples II and III, Table 1) were prepared in the manner U described in Example I. The results of firing tests carried out with these explosive compositions are reported in Table 1.

. EXAMPLES IV-XXII A number of other explosive compositions were pre-, pared in which the quantity of potassium dichromate was varied from to 6 percent by weight based on the weight Themethod of preparation was the same as that described in Example I.. The results of the firing tests conducted with these materials are also recorded in Table 1.

Table 1 CHROMATE -CONTAINING AMMONIUM NITRATE EXPLOSIVE COMPOSITIONS I Addition 7 Total l Potassium No. 2 Tempera Weight of Volume Example Dichromate Diesel ture of Explosive of Crater (Percent) Oil (Per- Potassium Charge (Cubic cent) Dic(l ir8n)1ate (Grams) Inches) 0.0 '5. 0 180 175 780 0. 0 5.0 185 210 1, 390 0. 0 5. 0 190 225 830 400 3, 020 0. 5. 0 175 200 1, 290 100 980 r 400 3, 640 0. 5 5. 0 180 200 1,590 88' r p 2 1, 0 0 0. a 5. 0 185 100 740 400 4, 740 1. 0 '5. 0 180 200 1, 840

100 88 400 3, 960 1. O 5. 0 185 200 2, 000 I l 100 990 l 400 8, 040 1.0 5. 0 v 190 200 3, 220 V, 100 1,600 l l 400 9, 890 1.5 5. 0 a 180 200 a, 090 V 7 100 1, 030 400 7, 360 l. 5 5.0 185 200 3, 140 100 2, 350 4 400 7,610 1. 5 5. 0' .190 200 1, 670 100 1, 510 400 2, 880 2. 0 5.0 .175 I *200 1, 750 100 1, 340 400 5, 390 2.0' 7 5.0 180 200 2,900 as 222 V 1, 2. 0 s. o 185 1700 780 about 170 C. to about 200 C., the amount of the said 7 Table IContiriued CHROJMATE-CONTAINING AMMONIUM. NITRATE EXPLOSIVE COMPOSITIONS-Continued Addition Total Potassium N0. 2" Tempera- Weight of Volume Example Dichromate Diesel ture of Explosive of Crater (Percent) Oil (Per- Potassium Charge (Cubic cent)? Diel romate (Grams) Inehesfl 4 3.0 5. 0 4 165-173 172 1, 63 4 3. 0 5.0 4 180-185 189 1, 63 p 400 8,81 3; 0 5.0 180 200 2, 60 100 l, 17 3. 0 5. 0 185 400 8, 64 400 7, 34 3.0 5. 0 190 200 3, 27 100 1, 74 180 B 200 2,89 XXI 3.0 5. 0 180 5 200 3, 77 I 180 7 200 3,08 400 6, 61 XXII 6. 0 5. 0 180 7 200 2, 4 100 a 8 1 Based on the weight of the ammonium nitrate.

Based on the combined weight of the ammonium nitrate and chromate sa t. a

All charges'were detonated with an Engineer Special Blasting Cap or equivalent cap. 4 In Examples II and III sodium dichromate (NazOr O1),was utilized rather than potassium dichromate.

Prepared from fused ammonium nitrate-potassium dichromate having a mesh size of 3 to 14. I

6 Prepared from fused ammonium nitrate-potassium L dichromate having a mesh size of 14 to 24.

1 Prepared from fused ammonium nitrate-potassium dichromate having a mesh size of 14 to 100.

What is claimed is:

1. A process for preparingv an explosive composition which comprises (A) forming an ammonium nitratechromatesalt melt'by admixing a chromate salt selected from the group consisting of the monochromates and dichromates of ammonia, sodium, potassium and lithium with molten ammonium nitrate at a temperature of from chromate salt being from about 0.5 to about 10 percent by weightof'the ammonium nitrate, (B) forming from the said melt a solid particulate material, and (C) admixing with the said solid particulate material a hydrocarbon oil which is a liquid at room temperature and atmospheric pressure.

2. The process of claim 1 wherein the said solid partic 5. The process of claim 1 wherein the amount of hy drocarbon oil admixed with the said solid particulate material is from about 3 to about 8 percent'by weight of the said solid particulate material.

6. The process of claim 1 wherein the hydrocarbon oil is No. 2 Diesel oil.

7. A process for preparing an explosive composition which comprises (A) forming an ammonium nitratepotassium dichromate melt by admixing potassium dichromate with molten ammonium nitrate at a temperature of from about C. to about 200 C., the amount ofthe said potassium dichromate being from about 0.5 to about 10 percent by weight of the ammonium nitrate, (B) reducing in size the solid produced on solidification of the said melt to a particulate material, and (C) admixing with the said particulate material a hydrocarbon oil which is a liquid at room temperature and atmospheric pressure in an amount of from about 3 to about 8 percent by weight of the particulate material.

8. An explosive composition consisting essentially of a hydrocarbon oil and a fused ammonium nitrate chromate cnce OOOOOOOOOOOOQOO 5 6 'monochromates and diehromates of ammonia, sodium, 10. The explosive composition of claim 8 wherein the potassium and lithium with molten ammonium nitrate chromate salt is sodium dichromate. at a temperature of from about 170 C. to about 200 C., 11. The explosive composition of claim 8 wherein the forming from the said melt a solid particulate material hydrocarbon oil is No.2 Diesel oil. .and admiring with the particulate material a hydrocar- 5 v bon oil which is liquid at room temperature and atmos- Refeimces Citad in the filt? of this Patent pheric pressure, said hydrocarbon oil being present in an UNlTED STATES PATENTS amount of from about 3 to about 8 percent by weight of L the said particulate composition, said chromate salt being 5 3 a1 g2 present in the said particulate composition in an amount 10 2997377 E a y 1 61 of from about 05 to about 10 percent by weight of the f we 2 9 ammonium nitrate. FOREIGN PATENTS 9. The explosive composition of claim 8 wherein the 6,327 Great Britain APR 27 1895 chromate salt is potassium dichromate. 

1. A PROCESS FOR PREPARING AN EXPLOSIVE COMPOSITION WHICH COMPRISES (A) FORMING AN AMMONIUM NITRATECHROMATE SALT MELT BY ADMIXING A CHROMATE SALT SELECTED FROM THE GROUP CONSISTING OF THE MONOCHROMATES AND DICHROMATES OF AMMONIA, SODIUM, POTASSIUM AND LITHIUM WITH MOLTEN AMMONIUM NITRATE AT A TEMPERATURE OF FROM ABOUT 170*C. TO ABOUT 200*C., THE AMOUNT OF THE SAID CHROMATE SALT BEING FROM ABOUT 0.5 TO ABOUT 10 PERCENT BY WEIGHT OF THE AMMONIUM NITRATE, (B) FORMING FROM THE SAID MELT A SOLID PARTICULATE MATERIAL, AND (C) ADMIXING WITH THE SAID SOLID PARTICULATE MATERIAL A HYDROCARBON OIL WHICH IS A LIQUID AT ROOM TEMPERATURE AND ATMOSPHERIC PRESSURE. 